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Case Study: California Apartment Complex with Solar Hot Water

Owners of California apartment buildings are one of the businesses that will benefit most from going with a solar hot water system.

Traditionally in California (and many states), apartment building landlords include hot water with every rental lease. Rather than individual hot water heaters, a central water heater (typically powered by gas) provides hot water to all residential units and onsite laundry facilities.

Consequently, with every bath, shower, dish washing, or load of laundry, the landlord is spending money to heat the hot water for the building’s residents. Installing a solar hot water system is a way to save 80% of that solar hot water cost.

Let’s take an example of an apartment or condo complex with about 120 units and 160 residents. While this is a real life example, please remember that every apartment building is unique with different requirements and water usage. For each unit the calculation is as follows: 20 gallons per person per-day for the first person, 15 gallons per-day for the second, and 10 gallons per-day for each person thereafter.  Also included in the calculation are the 12 front-load energy saving washers to a total hot water consumption of 3,000 gal/day

So, even if you own another 160 resident building in California, your costs may be more or less than the following example.

Solar Hot Water Cost and Savings Example for a California Apartment Building with 160 Residents

Utility PG&E
Min.Daily Demand @ 80% BTU 1,875,150
Est. Water Storage Requirements 3,000 Gallons
# of Free Hot Water 7000 collectors: 66 panels
Roof area required: 3,500 sq. ft
Est. gas bill for hot water before solar: $16,000/year
Est. Cost before rebate, incl. engineering $180,000
Estimated California Rebate: $ -86,000
Estimated 30% Federal Tax Credit: $ -54,000*
Estimated Net System Cost: $40,000
Estimated Payback time: About 3 yrs!
CO2 Saved from the environment over 25 years: 3 Metric Tons
* Marcs 5 yr accelerated depreciation may be available and is not included in the ROI calculations.  Please consult with your tax attorney as for your eligibility.  

Once again, it should be noted that every apartment building is different. The number of units, number of residents, type of washers, type of dish washers, hot water tanks, engineering, roof space and many other factors will affect individual costs.

Also, these figures are rounded and based on the expected PG&E rebate. However, as of August 2010, the rebate regulations are still being finalized by The California Public Utility Commissions (CPUC) may alter these numbers.

According to sources, the CPUC should finalize the regulations by some time in September. Consequently, now is the time to get your solar quote and start the design and engineering to get reserved on the first tier of California rebates. Rebate amounts will decrease as the number of installations rise, so early adopters will get the most generous part of the subsidies.

In addition to California, there are other states that have very generous rebates right now. Contact us at info@freehotwater.com to get the latest information of your state.

Finally, remember that there’s no cost to getting a customized quote for your apartment building or other business. Worse come to worse, you’ll spend a little time getting educated about solar hot water. Best case, you’ll save a lot of money going solar.

When designing a large scale system, we have to consider for microclimate and local radiation as well as water demand, pick hours and water consumption patterns.

If you have any questions about the above, please contact us.

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2 Responses to Case Study: California Apartment Complex with Solar Hot Water

  1. GetSolar says:

    Hi Solar Fred,

    Thanks for this post! We’ve done some similar analysis, but have never seen the numbers for such a large building with high hot water use. $16,000 annually spent on natural gas is incredibly high–no wonder solar looked like a good option.

    We’re looking forward to future posts!


  2. Solar Fred says:

    Hey, Guys,

    Apartment buildings, hotels, and many other retail industries all use a tremendous amount of hot water, typically heated by gas, but sometimes oil. This is actually just a small example of 160 units. Other buildings have even more units, so you can imagine the yearly costs and carbon footprint.